Improvement in lightning-rods



1. M. M o TT.y

Lightnig-Rnds.

Patented June 16, 1874.

UNITED STATES PATENT OFFICE JOHN M. MOTT, OF CHICAGO, ILLINOIS.

IMPROVEMENT IN LIGHTNING-RODS.

Specification forming part of Letters Patent No. 152,153, dated June 16,1874; application tiled January 11, 1873.

To all whom it may concern:

Beit known that I, JOHN M. Mo'r'r, of Chicago, in the county of Cook andState of Illinois, have invented a new and valuable Improvement inLightning-Rods; and I do hereby declare that the following is a full,clear, and exact description of the construction and operation of thesame, reference being had to the annexed drawings making a part of thisspeciiication, and to the letters and igures of reference markedthereon.

Figure l of the drawings is a representation of a perspective view of myrod joined. Fig. 2 is a perspective view of separated joint, showingdowelpin. Fig. 3 is a transverse section of rod.

This invention has relation to the construction of lightniug-rods whichare made, of sheetcopper or other metal, in the hollow or tubular form;and it consists in longitudinally folding the strip of sheet-copper in apeculiar convolute or scroll shape, in such a manner as to form fourparallel tubes in the same continuous strip, having the relation to eachother, in the crosssection, of the four corners of' a parallelogram. Italso consists in the construction and novel arrangement of the smallsolid couplingrods or dowels in two opposite tubes, whereby the sectionsof the lightning rod are connected together in such a manner that thecon tin nity of the copper surface is not broken or obstructed, and therod is even more firm at the `joints than at the intermediate portions.

In the accompanying drawings, the letters A A designate the sections ofthe rod. Each section is formed by bending the copper sheetlongitudinally in scroll form, forming the convolutions first on oneside, and then on the other, in the manner shown at Fig. 3 of thedrawings, each convolution being bent entirely around, forming acomplete tube, as shown at b b of the drawings, and the wall of eachtube being a part of the same continuous sheet. In the drawings thesheet is represented as being bent into four convolutions or tubes,which are irmly bound together by the contin nous wall, forming a rod ofexceeding rigidity.

It will be observed that in the cross-section of this rod the four tubesoccupy the four corners of a parallelogram; and, as the dowel-pins areintroduced in two opposite tubes, the other two tubes, being arrangedone on one side and the other on the other side of the plane of thedodveled tubes, serve to brace the joint on each s1 e.

As this rod is more readily manufactured in sections, the couplingdowelsc are employed to connect the sections. These dowels are secured, for ashort distance above and below the joint, in two or more of the tubes ofeach section, thus forming a secure coupling, which will keep the rodrigid at the joint without obstructing the interior or exterior surfacesof the copper. A slight twist is designed to be given to the sections,for the purpose of making the eonvolutions somewhat more secure 5 butthis is not indispensable. A key, d, is enr ployed to keep the sectionsfrom parting longitudinally. It is designed to pass through the walls ofthe convolutions and through the coupling-dowels.

What I claim as my invention, and desire to secure by Letters Patent,is-

The lightning-rod or section thereof formed by folding a continuoussheet of metal into four tubular convolutions, oceupyin g, in crosssection, the four corners of a parallelograni, slightly twisting thesame, and providing two opposite tubes with solid dowel-pins forconnecting the sections, in the manner herein shown and described.

In testimony that I claim the above I have hereunto subscribed my namein the presence of two witnesses.

JOHN M. MOTT..

fitnesscsz C. S. MoTT, Rois. STonEE Morir.

